BASIC SEPARATION THEORY DOE-HDBK-1015/1-93 Appendix A CH-01 Rev. 0 Page A-10 CONVERTERS Converters The actual separation of U    F  from U    F  in a gaseous diffusion plant is accomplished in the 235 238 6 6 converter.  The converter, sometimes referred to as a diffuser, contains the barrier tubing through which diffusion takes place.  In the previous section we studied the flow through the converter as a part of a stage.  In this section we will see what takes place inside the converter. In all, the entire cascade contains over 4000 converters -- one in each stage.  The stage size varies with the location in the cascade as shown in the table below. TABLE A-1 Converter Stage Size vs. Location Equipment Converter Length Diameter Number Type Type (inches) (inches) Used In Cascade 33 000 291 155 640 31 00-2 221 105 500 29 0 185 or 215 90 or 105 600 27 7 129 47 720 25 8 129 38 1560 Converter Construction Externally, the converter resembles a large cylindrical tank resting on its side (see Figure A-4). There are openings at each end for the necessary piping connections.  The outlet end of the converter contains the "A" and "B" stream process gas outlets.  The other end contains the mixed process gas inlet and the stage coolant inlet and outlet.  The cylindrical tank is called the shell and is constructed of steel with welded joints.  Its internal surface is nickel plated.  There are three external reinforcing flanges around the outside of the shell.  The many hundreds of barrier tubes, or tube bundles, contained in one converter are held in place by the spool, or spool piece.  The spool consists of struts and a central tube, or core, which is perforated and allows part of the "A" stream leaving the barrier tubes to reach the converter outlet.  On either end of the core are tube sheets into the holes of which the barrier tubes are sealed by rolling or swagging.  Tube sheets are also mounted on the core between the end tube sheets to support the barrier tubes.